Adding extra keyword in search hurts search ranking?

[vinceeee]

So I have just made a modification to my keywords and added the word design in it. Now if I use for example “business logo” or “modern logo” in search I end up on the second page which is pretty good. But if I add the word design in search so for example “business logo design” or “modern logo design” I go from page 2 to page 7 and 9. Could someone explain this ? And possibly give a tip on how to get higher when adding “design” ? Thank you ! 🙂